The present invention relates to substituted piperazine derivatives of general formula 
their isomers, their salts, particularly the physiologically acceptable salts thereof which have valuable pharmacological properties.
The compounds of the above general formula I are valuable inhibitors of the microsomal triglyceride-transfer protein (MTP) and are therefore suitable for lowering the plasma level of the atherogenic lipoproteins.
In the above general formula I
n denotes the number 1, 2, 3, 4 or 5,
m denotes the number 2 or 3,
X denotes a carbon-carbon bond, an oxygen atom, a methylene, ethylene, imino or N-(C1-3-alkyl)-imino group,
Ra denotes a phenyl group or heteroaryl group substituted by the groups R1 and R2, wherein
R1 denotes a hydrogen, fluorine, chlorine or bromine atom, a C1-3-alkyl group wherein the hydrogen atoms may be wholly or partly replaced by fluorine atoms, a hydroxy group, a C1-4-alkoxy group wherein the hydrogen atoms may be wholly or partly replaced by fluorine atoms, a phenoxy, heteroaryloxy, phenyl-C1-3-alkoxy, carboxy, C1-3-alkoxycarbonyl, aminocarbonyl, C1-3-alkylaminocarbonyl, N,N-di-(C1-3-alkyl)-aminocarbonyl, nitro, amino, C1-3-alkylamino, di-(C1-3-alkyl)-amino, phenyl-C1-3-alkyl-amino, N-(C1-3-alkyl)-phenyl-C1-3-alkylamino, C1-3-alkylcarbonylamino, N-(C1-3-alkyl)-C1-3-alkylcarbonyl-amino, C1-3-alkylsulphonyl-amino or N-(C1-3-alkyl)-C1-3-alkylsulphonylamino group, while the abovementioned phenyl or heteroaryl moieties of the group R1 may be substituted by one to five fluorine, chlorine or bromine atoms, a C1-3-alkyl group wherein the hydrogen atoms may be wholly or partly replaced by fluorine atoms, a hydroxy group, or a C1-4-alkoxy group wherein the hydrogen atoms may be wholly or partly replaced by fluorine atoms, and
R2 denotes a hydrogen, fluorine, chlorine or bromine atom, a C1-3-alkyl group wherein the hydrogen atoms may be wholly or partly replaced by fluorine atoms, or a C1-4-alkoxy group wherein the hydrogen atoms may be wholly or partly replaced by fluorine atoms, or
R1 and R2 together represent a methylenedioxy group, or Ra denotes a monocyclic heteroaryl or phenyl group which is substituted in each case by a phenyl or monocyclic heteroaryl group, while the abovementioned phenyl groups and heteroaryl groups may in each case be substituted by a fluorine, chlorine or bromine atom, a C1-3-alkyl group wherein the hydrogen atoms may be wholly or partly replaced by fluorine atoms, by a hydroxy, C1-3-alkoxy, carboxy, C1-3-alkoxycarbonyl, amino-carbonyl, C1-3-alkylaminocarbonyl or N,N-di-(C1-3-alkyl)-aminocarbonyl group,
Rb and Rc independently of one another denote a hydrogen atom or a C1-3-alkyl group and
Rf and Rg, which may be identical or different, denote hydrogen atoms, C1-6-alkyl groups wherein the hydrogen atoms may be wholly or partly replaced by fluorine atoms, C3-7-cycloalkyl groups, phenyl, heteroaryl, phenyl-C1-3-alkyl or heteroaryl-C1-3-alkyl groups, while the abovementioned phenyl groups and heteroaryl groups may in each case be substituted by one to three fluorine, chlorine or bromine atoms, by one to three C1-3-alkyl groups wherein the hydrogen atoms may be wholly or partly replaced by fluorine atoms, by one to three hydroxy groups, one to three C1-3-alkoxy groups wherein the hydrogen atoms may be wholly or partly replaced by fluorine atoms, or by a carboxy, C1-3-alkoxycarbonyl, aminocarbonyl, C1-3-alkylaminocarbonyl, N,N-di-(C1-3-alkyl)-aminocarbonyl, N,N-di-(C1-3-alkyl)-amino, nitro or amino group, or
Rf and Rg together with the nitrogen atom between them denote a 3- to 7-membered cycloalkyleneimino group, while the methylene group in the 4 position of a 6- or 7-membered cycloalkyleneimino group may additionally be replaced by an oxygen or sulphur atom, by a sulphinyl, sulphonyl, imino or N-(C1-3-alkyl)-imino group,
while the tricyclic group in the abovementioned general formula I may be mono- or disubstituted by fluorine or chlorine atoms, by methyl or methoxy groups and the substituents may be identical or different.
By the abovementioned heteroaryl groups are meant 6-membered heteroaryl groups containing one, two or three nitrogen atoms, or 5-membered heteroaryl groups which may contain one to four heteroatoms such as, for example, nitrogen, oxygen and sulphur, while hydrogen atoms bound to nitrogen may optionally be replaced by C1-3-alkyl groups.
Preferred compounds of the above general formula I are those wherein
n denotes the number 3, 4 or 5,
m denotes the number 2 or 3,
X denotes a carbon-carbon bond, an oxygen atom, a methylene, ethylene, imino or N-(C1-3-alkyl)-imino group,
Ra denotes a phenyl group or heteroaryl group substituted by the groups R1 and R2, wherein
R1 denotes a hydrogen, fluorine, chlorine or bromine atom, a C1-3-alkyl group wherein the hydrogen atoms may be wholly or partly replaced by fluorine atoms, a hydroxy group, a C1-4-alkoxy group wherein the hydrogen atoms may be wholly or partly replaced by fluorine atoms, a phenoxy, heteroaryloxy, phenyl-C1-3-alkoxy, carboxy, C1-3-alkoxycarbonyl, aminocarbonyl, C1-3-alkylaminocarbonyl, N,N-di-(C1-3-alkyl)-aminocarbonyl, nitro, amino, C1-3-alkylamino, di-(C1-3-alkyl)-amino, phenyl-C1-3-alkyl-amino, N-(C1-3-alkyl)-phenyl-C1-3-alkylamino, C1-3-alkylcarbonylamino, N-(C1-3-alkyl)-C1-3-alkyl-carbonylamino, C1-3-alkylsulphonylamino or N-(C1-3-alkyl)-C1-3-alkylsulphonylamino group, while the abovementioned phenyl or heteroaryl moieties of the group R1 may be substituted by one to five fluorine, chlorine or bromine atoms, a C1-3-alkyl group wherein the hydrogen atoms may be wholly or partly replaced by fluorine atoms, a hydroxy group, or a C1-4-alkoxy group wherein the hydrogen atoms may be wholly or partly replaced by fluorine atoms, and
R2 denotes a hydrogen, fluorine, chlorine or bromine atom, a C1-3-alkyl group wherein the hydrogen atoms may be wholly or partly replaced by fluorine atoms, or a C1-4-alkoxy group wherein the hydrogen atoms may be wholly or partly replaced by fluorine atoms, or
R1 and R2 together represent a methylenedioxy group,
or Ra denotes a monocyclic heteroaryl or phenyl group which is substituted in each case by a phenyl or monocyclic heteroaryl group, while the abovementioned phenyl groups and heteroaryl groups may in each case be substituted by a fluorine, chlorine or bromine atom, a C1-3-alkyl group wherein the hydrogen atoms may be wholly or partly replaced by fluorine atoms, by a hydroxy, or C1-3-alkoxy group,
Rb and Rc independently of one another denote a hydrogen atom or a C1-3-alkyl group and
Rf and Rg, which may be identical or different, denote hydrogen atoms, C1-6-alkyl groups wherein the hydrogen atoms may be wholly or partly replaced by fluorine atoms, C3-7-cycloalkyl groups, phenyl, heteroaryl, phenyl-C1-3-alkyl or heteroaryl-C1-3-alkyl groups, while the abovementioned phenyl groups and heteroaryl groups may in each case be substituted by one to three fluorine, chlorine or bromine atoms, by one to three C1-3-alkyl-groups, wherein the-hydrogen-atoms may be wholly or partly replaced by fluorine atoms, by one to three hydroxy groups, one to three C1-3-alkoxy groups wherein the hydrogen atoms may be wholly or partly replaced by fluorine atoms, or by a carboxy, C1-3-alkoxycarbonyl, aminocarbonyl, C1-3-alkylaminocarbonyl, N,N-di-(C1-3-alkyl)-aminocarbonyl, N,N-di-(C1-3-alkyl)-amino, nitro or amino group, or
Rf and Rg together with the nitrogen atom between them denote a 3- to 7-membered cycloalkyleneimino group, while the methylene group in the 4 position of a 6- or 7-membered cycloalkyleneimino group may additionally be replaced by an oxygen or sulphur atom, by a sulphinyl, sulphonyl, imino or N-(C1-3-alkyl)-imino group,
the isomers and the salts thereof.
Particularly preferred compounds of the above general formula I are those wherein
n denotes the number 3, 4 or 5,
m denotes the number 2 or 3,
X denotes a carbon-carbon bond or an oxygen atom,
Ra is as hereinbefore defined, and
Rb and Rc independently of one another denote a hydrogen atom or a methyl group and
Rf denotes a hydrogen atom, a C1-6-alkyl group wherein the hydrogen-atoms may be wholly or partly replaced by fluorine atoms, a C3-7-cycloalkyl group, phenyl, heteroaryl, phenyl-C1-3-alkyl or heteroaryl-C1-3-alkyl group, while the abovementioned phenyl groups and heteroaryl groups may in each case be substituted by one to three fluorine, chlorine or bromine atoms, by one to three C1-3-alkyl groups wherein the hydrogen atoms may be wholly or partly replaced by fluorine atoms, by one to three hydroxy groups, one to three C1-3-alkoxy groups wherein the hydrogen atoms may be wholly or partly replaced by fluorine atoms, or by a nitro or amino group, and
Rg denotes a hydrogen atom,
the isomers and the salts thereof.
The following are mentioned as examples of particularly valuable compounds:
(a) 9-[4-(4-biphenyl-3-yl-piperazin-1-yl)-butyl]-9H-fluorene-9-carboxylic acid-(2,2,2-trifluoroethyl)-amide and
(b) 9-[4-(4-biphenyl-4-yl-piperazin-1-yl)-butyl]-9H-fluorene-9-carboxylic acid-(2,2,2-trifluoroethyl)-amide,
the isomers and the salts thereof.
According to the invention, the new compounds are obtained by methods known from the literature, for example by the following methods:
a. reacting a compound of general formula 
wherein
Ra, Rb and Rc are as hereinbefore defined, with a compound of general formula 
wherein n, Rf, Rg and the tricyclic system are as hereinbefore defined and
Z1 denotes a nucleofugic leaving group such as a halogen atom, e.g. a chlorine, bromine or iodine atom.
The reaction is preferably carried out in a solvent such as methylene chloride, acetonitrile, tetrahydrofuran, toluene, acetone/water, dimethylformamide or dimethylsulphoxide, optionally in the presence of a base such as sodium hydride, potassium carbonate, potassium tert-butoxide or N-ethyl-diisopropylamine at temperatures between 0 and 100xc2x0 C., preferably at temperatures between 10 and 60xc2x0 C.
b. reacting a compound of general formula 
wherein
the tricyclic system is as hereinbefore defined, with an amine of general formula 
wherein
Rf and Rg are as hereinbefore defined, or with the reactive derivatives thereof.
The reaction is expediently carried out with a corresponding halide or anhydride of general formula IV in a solvent such as methylene chloride, chloroform, carbon tetrachloride, ether, tetrahydrofuran, dioxane, benzene, toluene, acetonitrile or sulfolane, optionally in the presence of an inorganic or organic base at temperatures between xe2x88x9220 and 200xc2x0 C., but preferably at temperatures between xe2x88x9210 and 160xc2x0 C. It may also, however, be carried out with the free acid, optionally in the presence of an acid-activating agent or a dehydrating agent, e.g. in the presence of isobutyl chloroformate, thionyl chloride, trimethylchlorosilane, hydrogen chloride, sulphuric acid, methanesulphonic acid, p-toluenesulphonic acid, phosphorus trichloride, phosphorus pentoxide, N,Nxe2x80x2-dicyclohexylcarbodiimide, N,Nxe2x80x2-dicyclohexyl carbodiimide/N-hydroxysuccinimide or 1-hydrbxybenzotriazole, N,Nxe2x80x2-carbonyldiimidazole or N,Nxe2x80x2-thionyldiimidazole or triphenylphosphine/carbon tetrachloride, at temperatures between xe2x88x9220 and 200xc2x0 C., but preferably at temperatures between xe2x88x9210and 160xc2x0 C.
If according to the invention a compound of general formula I is obtained which contains a nitro group, it may be converted by reduction into a corresponding amino compound or
if a compound of general formula I is obtained wherein Rf denotes a hydrogen atom, it may be converted by alkylation into a corresponding compound wherein Rf denotes a C1-3-alkyl or phenyl-C1-3-alkyl group.
The subsequent reduction of a nitro group is expediently carried out hydrogenolytically, e.g. with hydrogen in the presence of a catalyst such as platinum, palladium/charcoal or Raney nickel in a suitable solvent such as methanol, ethanol, ethyl acetate, tetrahydrofuran, dioxane, dimethylformamide or glacial acetic acid, optionally with the addition of an acid such as hydrochloric acid and at a hydrogen pressure of 1 to 7 bar, but preferably 1 to 5 bar, with metals such as iron, tin or zinc in the presence of an acid such as acetic acid or hydrochloric acid, with salts such as iron(II)sulphate, tin (II) chloride, sodium sulphide, sodium hydrogen sulphite or sodium dithionite, or with hydrazine in the presence of Raney nickel at temperatures between 0 and 100xc2x0 C., but preferably at temperatures between 20 and 60xc2x0 C.
The subsequent alkylation is optionally carried out in a solvent or mixture of solvents such as methylene chloride, dimethylformamide, benzene, toluene, chlorobenzene, tetrahydrofuran, benzene/tetrahydrofuran, dioxane, dimethylsulphoxide or sulfolane with an alkylating agent such as a corresponding halide or sulphonic acid ester, e.g. with methyl iodide, ethyl bromide, dimethylsulphate or benzyl chloride, optionally in the presence of a tertiary organic base or in the presence of an inorganic base, expediently at temperatures between 0 and 150xc2x0 C., preferably at temperatures between 0 and 100xc2x0 C.
In the reactions described hereinbefore, any reactive groups present such as hydroxy, carboxy, amino, alkylamino or imino groups may be protected during the reaction by conventional protecting groups which are cleaved again after the reaction.
For example, a protecting group for a hydroxy group may be a trimethylsilyl, tert.butyl-dimethylsilyl, acetyl, benzoyl, methyl, ethyl, tert.butyl, trityl, benzyl or tetrahydropyranyl group,
a protecting group for a carboxyl group may be a trimethylsilyl, methyl, ethyl, tert.butyl, benzyl or tetrahydropyranyl group and
protecting groups for an amino, alkylamino or imino group may be a formyl, acetyl, trifluoroacetyl, ethoxycarbonyl, tert.butoxycarbonyl, benzyloxycarbonyl, benzyl, methoxybenzyl or 2,4-dimethoxybenzyl group and additionally, for the amino group, a phthalyl group.
Any protecting group used is optionally subsequently cleaved for example by hydrolysis in an aqueous solvent, e.g. in water, isopropanol/water, acetic acid/water, tetrahydrofuran/water or dioxane/water, in the presence of an acid such as trifluoroacetic acid, hydrochloric acid or sulphuric acid or in the presence of an alkali metal base such as sodium hydroxide or potassium hydroxide or aprotically, e.g. in the presence of iodotrimethylsilane, at temperatures between 0 and 120xc2x0 C., preferably at temperatures between 10 and 100xc2x0 C. However, a silyl group may also be cleaved using tetrabutylammonium fluoride as described hereinbefore.
However, a benzyl, methoxybenzyl or benzyloxycarbonyl group is cleaved for example hydrogenolytically, e.g. with hydrogen in the presence of a catalyst such as palladium/charcoal in a suitable solvent such as methanol, ethanol, ethyl acetate or glacial acetic acid, optionally with the addition of an acid such as hydrochloric acid at temperatures between 0 and 100xc2x0 C., but preferably at temperatures between 20 and 60xc2x0 C., and at a hydrogen pressure of 1 to 7 bar, but preferably 3 to 5 bar. A 2,4-dimethoxybenzyl group, however, is preferably cleaved in trifluoroacetic acid in the presence of anisole.
A tert.butyl or tert.butyloxycarbonyl group is preferably cleaved by treating with an acid such as trifluoroacetic acid or hydrochloric acid or by treating with iodotrimethylsilane, optionally using a solvent such as methylene chloride, dioxane, methanol or diethyl ether.
A trifluoroacetyl group is preferably cleaved by treating with an acid such as hydrochloric acid, optionally in the presence of a solvent such as acetic acid at temperatures between 50 and 120xc2x0 C. or by treating with sodium hydroxide solution, optionally in the presence of a solvent such as tetrahydrofuran at temperatures between 0 and 50xc2x0 C.
A phthalyl group is preferably cleaved in the presence of hydrazine or a primary amine such as methylamine, ethylamine or n-butylamine in a solvent such as methanol, ethanol, isopropanol, toluene/water or dioxane at temperatures between 20 and 50xc2x0 C.
Moreover, the compounds of general formula I obtained maybe resolved into their enantiomers and/or diastereomers, as mentioned hereinbefore. Thus, for example, cis/trans mixtures may be resolved into their cis and trans isomers, and compounds with at least one optically active carbon atom may be separated into their enantiomers.
Thus, for example, the cis/trans mixtures may be resolved by chromatography into the cis and trans isomers thereof, the compounds of general formula I obtained which occur as racemates may be separated by methods known per se (cf. Allinger N. L. and Eliel E. L. in xe2x80x9cTopics in Stereochemistryxe2x80x9d, Vol. 6, Wiley Interscience, 1971) into their optical antipodes and compounds of general formula I with at least 2 asymmetric carbon atoms may be resolved into their diastereomers on the basis of their physical-chemical differences using methods known per se, e.g. by chromatography and/or fractional crystallisation, and, if these compounds are obtained in racemic form, they may subsequently be resolved into the enantiomers as mentioned above.
The enantiomers are preferably separated by column separation on chiral phases or by recrystallisation from an optically active solvent or by reacting with an optically active substance which forms salts or derivatives such as e.g. esters or amides with the racemic compound, particularly acids and the activated derivatives or alcohols thereof, and separating the diastereomeric mixture of salts or derivatives thus obtained, e.g. on the basis of their differences in solubility, whilst the free antipodes may be released from the pure diastereomeric salts or derivatives by, the action of suitable agents. Optically active acids in common use are e.g. the D- and L-forms of tartaric acid or dibenzoyltartaric acid, di-o-tolyltartaric acid, malicacid, mandelic acid, camphorsulphonic acid, glutamic acid, aspartic acid or quinic acid. Anoptically active alcohol may be, for example, (+) or (xe2x88x92)-menthol and an optically active acyl group in amides may be, for example, a (+)- or, (xe2x88x92)-menthyloxycarbonyl.
Furthermore, the compounds of formula I obtained may be converted into the salts thereof, particularly for pharmaceutical use into the physiologically acceptable salts with inorganic or organic acids. Acids which may be used for this purpose include for example hydrochloric acid, hydrobromic acid, sulphuric acid, phosphoric acid, fumaric acid, succinic acid, lactic acid, citric acid, tartaric acid or maleic acid.
Moreover, if the new compounds of formula I thus obtained contain an acidic group such as a carboxy group, they may subsequently, if desired, be converted into the salts thereof with inorganic or organic bases, particularly for pharmaceutical use into the physiologically acceptable salts thereof. Suitable bases for this purpose include for example sodium hydroxide, potassium hydroxide, arginine, cyclohexylamine, ethanolamine, diethanolamine and triethanolamine.
The compounds of general formulae II to VI used as starting materials are known from the literature in some cases or may be obtained by methods known from the literature or are described in the Examples.
The compounds of general formula II are obtained, for example, by reacting a compound of general formula 
wherein Rb and Rc are as hereinbefore defined, Z2 denotes a protecting group for an amino group, e.g. the tert.butoxycarbonyl or benzyloxycarbonyl group, and Raxe2x80x2 denotes, for example, a phenyl or monocyclic heteroaryl group substituted by a bromine or iodine atom, with a, for example, trifluoromethyl-substituted monocyclic aryl or heteroaryl group which is additionally substituted by a boric acid group, in the presence of a catalyst such as palladium acetate, a base such as potassium tert.butoxide and a phase transfer catalyst such as tetrabutylammonium iodide in a solvent such as water, DMF, toluene or mixtures thereof at temperatures of between 20 and 130xc2x0 C. The protecting group is cleaved by methods known from the literature and leads to a compound of general formula II.
A compound of general formula III is obtained, for example, by reacting a corresponding disubstituted carboxylic acid with an xcex1,xcfx89-dihaloalkane in the presence of a strong base such as lithium diisopropylamide, sodium amide or sodium hydride and subsequently reacting the carboxylic acid with a corresponding amine.
As already mentioned hereinbefore, the compounds of general formula I and the physiologically acceptable salts thereof have valuable pharmacological properties. In particular, they are valuable inhibitors of the microsomal triglyceride-transfer protein (MTP) and are therefore suitable for lowering the plasma levels of the atherogenic lipoproteins.
For example, the compounds according to the invention were investigated for their biological effects as follows:
Inhibitors of MTP were identified by a cell-free MTP activity kit. Solubilised liver microsomes from various species (e.g. rat, pig) could be used as the MTP source. To prepare donor and acceptor vesicles, lipids dissolved in organic solvents were mixed in suitable proportions and applied in a thin layer to the wall of a glass container by blowing the solvent in a nitrogen current. The solution used to prepare donor vesicles contained 400 xcexcM phosphatidylcholine, 75 xcexcM cardiolipin and 10 xcexcM [14C]-triolein (68.8 xcexcCi/mg). To prepare acceptor vesicles, a solution of 1.2 mM phosphatidylcholine, 5 xcexcM triolein and 15 xcexcM [3H]-dipalmitoylphosphatidylcholine (108 mCi/mg) was used. Vesicles are formed by wetting the dried lipids with test buffer and then subjecting to ultrasound. Vesicle populations of uniform size were obtained by gel filtration of the ultrasonicated lipids. The MTP activity test contains donor vesicles, acceptor vesicles and the MTP source in test buffer. Substances were added from concentrated DMSO-containing stock solutions; the final concentration of DMSO in the test was 0.1%. The reaction was started by the addition of MTP. After a suitable incubation period the transfer process was stopped by the addition of 500 xcexcl of a SOURCE 30Q anion exchanger suspension (Pharmacia Biotech). The mixture was shaken for 5 minutes and the donor vesicles bound to the anion exchanger material were separated off by centrifuging. The radioactivity of [3H] and [14C] found in the supernatant was determined by liquid scintillation measurement and from this the recovery of the acceptor vesicles and the triglyceride transfer rate were calculated.
In view of the abovementioned biological properties the compounds of general formula I and the physiologically acceptable salts thereof are particularly suitable for lowering the plasma concentration of atherogenic apolipoprotein B (apoB)-containing lipoproteins such as chylomicrons and/or very low density lipoproteins (VLDL) as well as the residues thereof such as low density lipoproteins (LDL) and/or lipoprotein(a) (Lp(a)), for treating hyperlipidaemias, for preventing and treating atherosclerosis and the clinical sequela thereof, and for preventing and treating related disorders such as diabetes mellitus, adiposity and pancreatitis, oral administration being preferred.
The daily dose needed to achieve such an effect is between 0.5 and 500 mg, expediently between 1 and 350 mg, but preferably between 5 and 200 mg, in adults.
For this purpose, the compounds of formula I prepared according to the invention, optionally combined with other active substances such as other lipid-lowering agents, for example HMG-CoA-reductase inhibitors, cholesterol biosynthesis inhibitors such as squalene synthase inhibitors and squalene cyclase inhibitors, bile acid-binding resins, fibrates, cholesterol resorption inhibitors, niacin, probucol, CETP inhibitors and ACAT inhibitors may be incorporated together with one or more inert conventional carriers and/or diluents, e.g. with corn starch, lactose, glucose, microcrystalline cellulose, magnesium stearate, polyvinylpyrrolidone, citric acid, tartaric acid, water, water/ethanol, water/glycerol, water/sorbitol, water/polyethylene glycol, propylene glycol, cetylstearyl alcohol, carboxymethylcellulose or fatty substances such as hard fat or suitable mixtures thereof into conventional galenic preparations such as plain or coated tablets, capsules, powders, suspensions or suppositories.
The Examples that follow are intended to illustrate the invention: